Ischemic stroke classification

Ischemic Stroke Microchapters
Main Stroke Page
Transient ischemic attack
Hemorrhagic Stroke Page
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Stroke from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
CT
MRI
Echocardiography
Ultrasound
Other Imaging Findings
Treatment
Early Assessment
Medical Therapy
Surgery
Rehabilitation
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
AHA/ASA Guidelines for Stroke
Case Studies
Case #1
Ischemic stroke classification On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Ischemic stroke classification All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Ischemic stroke classification
CDC on Ischemic stroke classification
Ischemic stroke classification in the news
Blogs on Ischemic stroke classification
Directions to Hospitals Treating Stroke
Risk calculators and risk factors for Ischemic stroke classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Aysha Anwar, M.B.B.S[2]

Classification

.

Ischemic stroke

Based on duration of onset of symptoms

Based on cause

Transient Ischemic stroke (symptoms lasts <24 hrs)

Acute Ischemic stroke (symptoms lasts >24 hrs)

Chronic ischemic stroke

Thrombotic

Embolic 1.Atrial fibrillation 2.Fat 3.Septic 4.Air 5.Cancer

Vasculitic Giant cell arteritis Takayasu arteritis

Systemic hypoperfusion 1.Myocardial infarction 2.Pulmonary embolism 3.Pericardial effusion 4.Bleeding

TOAST classification 1.Large artery atherosclerosis 2.Cardioembolism 3.Small vessel occlusion 4.Stroke of determined etiology 5.Stroke of undetermined etiology

Arterial thrombosis 1.Carotid artery 2.Vertebral artery 3.Circle of Willis 4.Middle cerbral artery

Venous thrombosis Central venous thrombosis

Large vessel involvement 1.Atherosclerosis 2.Vasculitis 3.Noninflammatory vasculopathy 4.Fibromuscular dysplasia

Small vessel involvement 1.Fibrinoid degeneration 2.Lipohyalinosis 3.Microatheroma

Classification

Ischemic Stroke

In an ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction and necrosis of the brain tissue in that area. There are four reasons why this might happen: thrombosis (obstruction of a blood vessel by a blood clot forming locally), embolism (idem due to a embolus from elsewhere in the body, see below), systemic hypoperfusion (general decrease in blood supply, e.g. in shock) and venous thrombosis. Stroke without an obvious explanation is termed "cryptogenic" (of unknown origin).

Thrombotic Stroke

In thrombotic stroke, a thrombus (blood clot) usually forms around atherosclerotic plaques. Since blockage of the artery is gradual, onset of symptomatic thrombotic strokes is slower. A thrombus itself (even if non-occluding) can lead to an embolic stroke (see below) if the thrombus breaks off, at which point it is called an "embolus". Thrombotic stroke can be divided into two types depending on the type of vessel the thrombus is formed on:

• Large vessel disease involves the common and internal carotids, vertebral, and the Circle of Willis. Diseases that may form thrombi in the large vessels include (in descending incidence): atherosclerosis, vasoconstriction (tightening of the artery), aortic, carotid or vertebral artery dissection, various inflammatory diseases of the blood vessel wall (Takayasu arteritis, giant cell arteritis, vasculitis), noninflammatory vasculopathy, Moyamoya disease and fibromuscular dysplasia.
• Small vessel disease involves the smaller arteries inside the brain: branches of the circle of Willis, middle cerebral artery, stem, and arteries arising from the distal vertebral and basilar artery. Diseases that may form thrombi in the small vessels include (in descending incidence): lipohyalinosis (build-up of fatty hyaline matter in the blood vessel as a result of high blood pressure and aging) and fibrinoid degeneration (stroke involving these vessels are known as lacunar infarcts) and microatheroma (small atherosclerotic plaques).

Embolic Stroke

Embolic stroke refers to the blockage of an artery by an embolus, a traveling particle or debris in the arterial bloodstream originating from elsewhere. An embolus is most frequently a thrombus, but it can also be a number of other substances including fat (e.g. from bone marrow in a broken bone), air, cancer cells or clumps of bacteria (usually from infectious endocarditis).

Because an embolus arises from elsewhere, local therapy only solves the problem temporarily. Thus, the source of the embolus must be identified. Because the embolic blockage is sudden in onset, symptoms usually are maximal at start. Also, symptoms may be transient as the embolus is partially resorbed and moves to a different location or dissipates altogether.

Emboli most commonly arise from the heart (especially in atrial fibrillation) but may originate from elsewhere in the arterial tree. In paradoxical embolism, a deep vein thrombosis embolizes through an atrial or ventricular septal defect in the heart into the brain.

Cardiac causes can be distinguished between high- and low-risk:

• High risk: atrial fibrillation and paroxysmal atrial fibrillation, rheumatic disease of the mitral or aortic valve disease, artificial heart valves, known cardiac thrombus of the atrium or ventricle, sick sinus syndrome, sustained atrial flutter, recent myocardial infarction, chronic myocardial infarction together with ejection fraction <28 percent, symptomatic congestive heart failure with ejection fraction <30 percent, dilated cardiomyopathy, Libman-Sacks endocarditis, Marantic endocarditis, infective endocarditis, papillary fibroelastoma, left atrial myxoma and coronary artery bypass graft (CABG) surgery
• Low risk/potential: calcification of the annulus (ring) of the mitral valve, patent foramen ovale (PFO), atrial septal aneurysm, atrial septal aneurysm with patent foramen ovale, left ventricular aneurysm without thrombus, isolated left atrial "smoke" on echocardiography (no mitral stenosis or atrial fibrillation), complex atheroma in the ascending aorta or proximal arch

Systemic Hypoperfusion

Systemic hypoperfusion is the reduction of blood flow to all parts of the body. It is most commonly due to cardiac pump failure from cardiac arrest or arrhythmias, or from reduced cardiac output as a result of myocardial infarction, pulmonary embolism, pericardial effusion, or bleeding. Hypoxemia (low blood oxygen content) may precipitate the hypoperfusion. Because the reduction in blood flow is global, all parts of the brain may be affected, especially "watershed" areas - border zone regions supplied by the major cerebral arteries. Blood flow to these areas does not necessarily stop, but instead it may lessen to the point where brain damage can occur. This phenomenon is also referred to as "last meadow" to point to the fact that in irrigation the last meadow receives the least amount of water.

Venous Thrombosis

Cerebral venous sinus thrombosis leads to stroke due to locally increased venous pressure, which exceeds the pressure generated by the arteries. Infarcts are more likely to undergo hemorrhagic transformation (leaking of blood into the damaged area) than other types of ischemic stroke.

Hemorrhagic Stroke

CT scan showing an intracerebral hemorrhage.

Main articles: Intracranial hemorrhage and intracerebral hemorrhage

Based on location of the hemorrhage, hemorrhagic stroke may be classified into:

• Intracerebral hemorrhage (ICH)
• Subarachnoid hemorrhage

Intracranial hemorrhage is the accumulation of blood anywhere within the skull vault. A distinction is made between intra-axial hemorrhage (blood inside the brain) and extra-axial hemorrhage (blood inside the skull but outside the brain).

Intra-axial hemorrhage is due to intraparenchymal hemorrhage or intraventricular hemorrhage (blood in the ventricular system).

The main types of extra-axial hemorrhage are epidural hematoma (bleeding between the dura mater and the skull), subdural hematoma (in the subdural space) and subarachnoid hemorrhage (between the arachnoid mater and pia mater). Most of the hemorrhagic stroke syndromes have specific symptoms (e.g. headache, previous head injury).

Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a gradually enlarging hematoma (pooling of blood). It generally occurs in small arteries or arterioles and is commonly due to hypertension, trauma, bleeding disorders, amyloid angiopathy, illicit drug use (e.g. amphetamines or cocaine), and vascular malformations.

The hematoma enlarges until pressure from surrounding tissue limits its growth, or until it decompresses by emptying into the ventricular system, CSF or the pial surface.

A third of intracerebral bleed is into the brain's ventricles. ICH has a mortality rate of 44 percent after 30 days, higher than ischemic stroke or even the very deadly subarachnoid hemorrhage.

Stroke in the Young

This is a term used to describe stroke seen in individuals between 18 and 45 years of age. Common causes include:

• Cardiac - Congenital heart disease, atrial myxoma, patent foramen ovale, atrial fibrillation, rheumatic heart disease
• Vascular - Extracranial arterial dissection, hypertension, Moyamoya syndrome, migraine, vasospasm following subarachnoid hemorrhage
• Hematologic - Sickle cell disease, protein C deficiency, protein S deficiency, antithrombin III deficiency
• Infectious - Human Immunodeficiency Virus, varicella, bacterial meningitis, syphilis, tuberculosis
• Metabolic - Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, Fabry disease, mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes
• Drugs - Cocaine, methamphetamine, oral contraceptives